js贪吃蛇 javascript实现贪吃蛇小练习

时间:2021-01-29 余依忈人气:0

游戏思路：

创建方块、控制按钮（showBlock）
方块移动（点击开始，不断创建并移除前面的方块，用到队列先进先出）
控制移动（doUp\doDown\doLeft\doRight，加入用键盘控制）
产生食物方块(generateFood)
吃到食物变长（当方块位置相同时，吃食物）
判断撞墙、撞到自己游戏结束
设置积分

<!DOCTYPE html>
<html lang="en">

<head>
 <meta charset="UTF-8">
 <meta name="viewport" content="width=device-width, initial-scale=1.0">
 <title>Document</title>
</head>

<body>
 <style>
 body {
  margin: 0;
  padding: 0;
 }

 .content {
  width: 800px;
  height: 400px;
  background-color: gray;
  display: absolute;

 }
 </style>

 <div id="content" class="content">
 </div>
 <button onclick="start()">开始游戏</button>
 <button onclick="doUp()">上</button>
 <button onclick="doDown()">下</button>
 <button onclick="doLeft()">左</button>
 <button onclick="doRight()">右</button>
 <div id="score">0</div>

 <script>
 //定义参数
 var snackBlock = {};
 snackBlock.top = 20;
 snackBlock.left = 20;
 var firstDiv = showBlock(snackBlock.left, snackBlock.top, "red");
 var snackDivArray = [];//装方块的数组
 snackDivArray.push(firstDiv);

 var left = 1, right = 2, up = 3, down = 4;
 var direction = right;
 var food = generateFood();//生成食物
 var hasEat = false;
 var score = 0;


 function generateFood() {

  var left = getRandomNum(39);
  var top = getRandomNum(19);
  var foodBlock = showBlock(left, top, "pink");
  foodBlock.left = left;
  foodBlock.top = top;
  return foodBlock;
 }

 function getRandomNum(max) {
  return Math.round(Math.random() * max) * 20;
 }

 function start() {
  var interval = setInterval(function () {
  var newBlock = {};
  switch (direction) {
   case up:
   newBlock.top = snackBlock.top - 20;
   newBlock.left = snackBlock.left;
   break;
   case down:
   newBlock.top = snackBlock.top + 20;
   newBlock.left = snackBlock.left;
   break;
   case left:
   newBlock.top = snackBlock.top;
   newBlock.left = snackBlock.left - 20;
   break;
   case right:
   newBlock.top = snackBlock.top;
   newBlock.left = snackBlock.left + 20;
   break;

  }


  var currentLeft = newBlock.left;
  var currentTop = newBlock.top;
  var eat = false;

  //吃食物
  if (currentLeft == food.left && currentTop == food.top) {
   removeBlock(food);
   food = generateFood();
   eat = true;
   hasEat = true;
   score += 10;//吃一个加10分
   document.getElementById("score").innerHTML = score;//写入div
  }

  snackBlock = newBlock;
  //是否撞墙
  if (currentLeft < 0 || currentLeft >= 800 || currentTop < 0 || currentTop >= 400) {
   alert("game over!");
   clearInterval(interval);
   return;
  }
  if (eat == false) {
   //移除尾巴
   removeBlock(snackDivArray.shift(div));
  }
  //是否撞到自己
  snackDivArray.forEach(function (item, index, array) {
   if (item.top == currentTop && item.left == currentLeft) {
   alert("game over!");
   clearInterval(interval);
   return;
   }
  });

  //创建新的身体
  var div = showBlock(newBlock.left, newBlock.top, "red");
  div.left = newBlock.left;
  div.top = newBlock.top;
  snackDivArray.push(div);

  }, 300);

 }

 //方向控制
 function doUp() {
  if (direction == down && hasEat) {
  return;
  }
  direction = up;
 }
 function doDown() {
  if (direction == up && hasEat) {
  return;
  }
  direction = down;
 }
 function doRight() {
  if (direction == left && hasEat) {
  return;
  }
  direction = right;
 }
 function doLeft() {
  if (direction == right && hasEat) {
  return;
  }
  direction = left;
 }

 function showBlock(left, top, color) {//产生方块
  var content = document.getElementById("content");
  var snackDiv = document.createElement("div");
  snackDiv.style.width = "20px";
  snackDiv.style.height = "20px";
  snackDiv.style.left = left + "px";
  snackDiv.style.top = top + "px";
  snackDiv.style.background = color;
  snackDiv.style.position = "absolute";
  content.appendChild(snackDiv);
  return snackDiv;
 }
 function removeBlock(div) {//移除方块
  div.parentNode.removeChild(div);
 }
 //键盘控制方向
 document.onkeydown = function (e) {
  if (e && e.keyCode == 38) {
  doUp();
  } else if (e && e.keyCode == 40) {
  doDown();
  } else if (e && e.keyCode == 37) {
  doLeft();
  } else if (e && e.keyCode == 39) {
  doRight();
  }
 }
 </script>
</body>

</html>

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